Modern server farms or datacenters typically employ a large number of servers to handle processing needs for a variety of application services. Each server handles various operations and requires a certain level of power consumption to maintain these operations. Some of these operations are “mission critical” operations, interruptions to which may lead to significant security breach or revenue losses for users associated with these operations.
However, interruptions of an AC power to datacenters can be unpredictable. In some cases, power interruptions can force a sudden shutdown and/or possibly resulting in data losses. Datacenters typically have back-up powers (e.g., energy stored in batteries) to support power consumption during AC power interruptions. The sudden shutdown can be prevented if a datacenter maintains a certain level of backup power before an input power interruption occurs. But exact capacity of a battery system can be affected by many factors, such as nature of battery chemistry, or degradation of battery cells over time. It can be very difficult to predict an amount of charge stored in the battery system after recharging.